Perennial ryegrasses are popular for use in turfgrass providing quick germination, fine textured leaves, a dense forming sod, and high disease and insect resistance. Perennial ryegrasses provide an attractive lower maintenance, permanent lawn cover in cooler climates, and can be used for winter overseeding of dormant bermudagrass (Cynodon dactvlon) in warmer climates to provide green grass through the winter. Perennial ryegrasses have also been used in soil erosion control programs and as forage.
Perennial ryegrass (Lolium perenne L.), also called English ryegrass, is a temperate (cool-season) perennial grass that is native to Europe, temperate Asia, and North Africa. It has been widely distributed to other parts of the world, including North and South America, Europe, New Zealand, and Australia. Perennial ryegrass is valued for fast establishment, attractive turf, reduced tillage renovation applications, and use on heavy and waterlogged soils.
Forage-type perennial ryegrasses are important grasses in forage-livestock systems. High palatability and digestibility make this species highly valued for use in dairy and sheep forage systems. As a result, it often is the preferred forage grass in temperate regions of the world.
Use of perennial ryegrass for turf has increased in recent years with selection of more dense and persistent turf types. It is one of the most versatile of all turfgrass species. For turf, perennial ryegrass is used alone (straights), in blends with other perennial ryegrasses,or in mixtures with other grass species on home lawns, athletic fields, golf courses (fairways, roughs and tees), parks, schools, and industrial sites.
Glyphosate (N-(phosphonomethyl) glycine) is the active ingredient in glyphosate herbicides, such as TOUCHDOWN TOTAL® brand herbicide produced by Syngenta Crop Protection, Inc. (Greensboro, N.C.). Typically, glyphosate is formulated as a water-soluble salt such as an ammonium, alkylamine, alkali metal or trimethylsulfonium salt. One of the most common formulations is the isopropylamine salt of glyphosate, which is the form employed in TOUCHDOWN TOTAL® brand herbicide.
Glyphosate is a broad spectrum herbicide that inhibits the enzyme enolpyruvylshikimate-phosphate synthase (EPSPS). It is conventionally applied as an aqueous solution to the foliage of plants, where it is taken up into the leaves and transported throughout the plant. Commercial formulations of glyphosate may also include one or more surfactants to facilitate penetration of the active ingredient into the plant leaves, as well as compounds to enhance rainfastness. Numerous U.S. patents disclose various formulations of glyphosate, including U.S. Pat. Nos. 4,405,531; 5,118,338; 5,196,044; 5,639,711; 5,652,197; 5,679,621; and 5,750,468.
A limited amount of success has been reported in finding natural resistance to glyphosate herbicides in plants. This is beneficial in one respect since it indicates that the likelihood of glyphosate resistant populations of weeds arising is low, but it also means that a limited amount of naturally resistant desirable plant species are available. As a result, great care must be taken when applying glyphosate herbicides in the vicinity of desirable plants (such as crops, ornamentals, and grass turf). In particular, glyphosate herbicides are effective against all grass species, and therefore, application of glyphosate herbicides in perennial ryegrasses to control weed growth has resulted in significant turf damage.
New and improved perennial ryegrasses continue to be developed for use as improved turfgrass and for overseeding of athletic fields, home lawns, golf courses (fairways, roughs and tees), parks, schools, and industrial sites, and for use forage. Research studies have been conducted to identify promising perennial ryegrass varieties and hybrids which express improved traits, such as, turf quality, seedling vigor, weather tolerance, resistance to problematic diseases and pests, as well as, tolerance to applications of glyphosate herbicides.
The glyphosate tolerant perennial ryegrass ‘Replay’ plants and plant tissues of the present invention were developed for use as improved turfgrass and for winter overseeding of athletic fields, home lawns, golf courses (fairways, roughs and tees), parks, schools, and industrial sites. In addition, the distinctive genetic fingerprint for the glyphosate tolerant perennial ryegrass ‘Replay’ plant has been analyzed, and the EPSPS polypeptide comprising the amino acid sequence of SEQ ID NO:13, and the polynucleotide having the nucleotide sequence of SEQ ID NO:10 and encoding the EPSPS protein, involved in the regulation of glyphosate tolerance in perennial ryegrass plants and plant tissues have been identified.